2001 C320 Knocking noise
 

When starting my car after an extended idle time, I get a knocking from the dash area on the drivers side and below the steering wheel. The knocking is approximately 8 distinct knocks about a second apart. These knocks are very noticeable and annoying. It seems as though something is being blocked from moving properly. It also seems as though it could affect the air flow of the AC system in some way. Any help would be appreciated. Thanks.

RE: 2001 C320 Knocking noise
 

Hello. I have the same 01 c320 car with the same problem. Maybe it is not a problem after all...

RE: 2001 C320 Knocking noise
 

it must be the stepper motors for air flaps which do the self initialization.

RE: 2001 C320 Knocking noise
 

Ah, ive got this problem too. i found the other thread that has this discussion on it, but the last reply w/ what appears to the the solution is in french.

Sleepwalker: I have seen you mention it here and there that it is the stepper motor, but do you have a solution for this noise? or an explanation for exactly why this noise is occuring?? I have no idea what a stepper motor does... :(

thanks!

RE: 2001 C320 Knocking noise
 

it is the stepper motors as sleepwalker says the linkage breaks usually its the footwell flap motor linkage which has to be replaced its behind the radio and it is not easily replaced

RE: 2001 C320 Knocking noise
 

Okay,
I have this problem too. I have the WIS for my home PC and i followed the french guy's explination. Here is the interesting thing. I took the whole dash apart. Took me about 2 hours to do. The linkage that commonly breaks has already been replaced. So, i hooked up all the necessary electronics and started the car to see what is happening. The little motor moves the valve as it should, it closes it, then brings it to open. ONce it gets back to the open position, the linkage comes to rest on a little black piece of plastic that sticks out from where the motor bolts on. Okay, so the linkage hits this shelf (kind of like a stop) but the motor keeps trying to turn it in that direction. The motor is what is making the clicking noise. Problem is, why is it still trying to turn it beyond the little stop? Is the motor bad? We bought the car used. It didn't do it at first, then it got progressively worse. If you want to try to DIY, its not that hard, just use the french guy's pictures and the better part of a saturday. Any help on this would be awesome. I guess I could just buy a replacement motor to see if that is what it is, I think its only like $70 from the stealership. Better than $700 i guess.

Thanks to all who contribute to this.

RE: 2001 C320 Knocking noise
 

Well the car will have to sit for one more day, which makes the wife unhappy (since it's her car). I bought the new servo motor today but when I went to install it, it wouldn't line up. See, the linkage was replaced some time ago with the new reinforced style. There are two of them, one labeled 'L' for left, the other 'R' for right, There is a slight pitch difference in the hexagon. I think the dealer replaced it with the wrong one. IF you look at it, the change in pitch on the hexagon is just enough for it to fit the actualtor lever, snugly holding the vent in the closed position. IF you try to take off the linkage and turn it 60 degrees, it is too far the other way, suggesting that its the wrong piece. I will report back tomorrow i guess.

RE: 2001 C320 Knocking noise
 

Well, the lever that I had worked. I simply placed it on the servo and pressed down on it to make it advance a little. We put the car back together and no clicking. To all that have this problem, it is either the servo motor or the plastic lever. The servo was $83 from the stealership. I got the lever quoted at $20. So even if it is both, you are only set back $103 verses 700+ if they do it at dealer.

Good Luck to all.

FYI - Now that I'm comfortable with taking the dash apart, we are looking into a Command retrofit with the money we saved!

:D

RE: 2001 C320 Knocking noise
 

I have the steper motors and linkidge for $75 shipped :D